The 2018 FIFA World Cup begins this week in Russia, which is expected to welcome more than 1.5 million visitors from around the globe. The quadrennial tournament is among the most high-profile sporting events in the world, which also makes it a potential target for terrorists.

Teams will play World Cup games inside 12 venues, but crowds will congregate in large numbers across 11 Russian cities, including Moscow. For law enforcement tasked with monitoring and protecting crowds in these cities, detecting radioactive material is both critical and challenging. The consequences of a “dirty bomb” explosion could be significant for nearby fans as well as locals miles from an attack.

In Boston, which hosts highly attended events such as the Boston Marathon, Independence Day fireworks celebrations and parades for championship sports teams, multiple agencies cooperate to protect large crowds. The Boston Fire Department (BFD) special operations unit is among those responsible for public protection, and Chief Dennis Costin, the unit’s head, credits state-of-the-art radiation detection instruments for ensuring safety and efficiency.

“The peace of mind these instruments provide us and, by extension, the public is immeasurable,” says Chief Costin. “Keeping the public safe is our first and foremost priority. And at large public events, we need to do that with as little fanfare as possible.”

Costin’s team deploys more than 270 pocket-sized personal radiation detectors from Thermo Fisher. These units can passively detect localized radiation sources generated by man-made devices as unit members roam crowds. The advanced technology embedded in these devices can immediately differentiate between potentially harmful artificial sources and natural sources, giving confidence that a threat is indeed a threat before aggressive measures are undertaken.

“We have a multi-layered approach that allows us to mitigate something quickly without disrupting the event,” Chief Costin added. “We can only accomplish that if we have sophisticated equipment, especially small or handheld devices that allow us to make quick and confident decisions.”

The tragic 2013 Boston Marathon bombings are a stark reminder of the challenge of large-event surveillance. If the bombs detonated had contained radioactive material, the potential for harm would have extended far beyond those in the blast zones. But Chief Costin and his team would have been equipped to quickly assess the situation and determine the range and severity of exposure.

As 2018 World Cup organizers prepare for potential security threats, they will certainly embrace the latest technology. After all, as in Boston, hosting a safe and enjoyable event without incident is a source of pride. Fans will barely notice the people and technology protecting them, and this is by design.

“We have to be prepared and proactive, thinking through all potential scenarios so our response becomes second nature,” Chief Costin said. “That means we need to have the right technology, as well as a coordinated approach.”